EP1659831B1 - Dispositif d'eclairage pour voiture avec des LED's - Google Patents

Dispositif d'eclairage pour voiture avec des LED's Download PDF

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Publication number
EP1659831B1
EP1659831B1 EP05024986A EP05024986A EP1659831B1 EP 1659831 B1 EP1659831 B1 EP 1659831B1 EP 05024986 A EP05024986 A EP 05024986A EP 05024986 A EP05024986 A EP 05024986A EP 1659831 B1 EP1659831 B1 EP 1659831B1
Authority
EP
European Patent Office
Prior art keywords
led
current
temperature
lighting device
leds
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP05024986A
Other languages
German (de)
English (en)
Other versions
EP1659831A1 (fr
Inventor
Martin Pfeil
Christoph Kenn
Christian Spreitzer
Stephan Berlitz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Audi AG
Original Assignee
Audi AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Audi AG filed Critical Audi AG
Publication of EP1659831A1 publication Critical patent/EP1659831A1/fr
Application granted granted Critical
Publication of EP1659831B1 publication Critical patent/EP1659831B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H05B45/18—Controlling the intensity of the light using temperature feedback
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/56—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits involving measures to prevent abnormal temperature of the LEDs
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light
    • H05B45/28—Controlling the colour of the light using temperature feedback

Definitions

  • the invention relates to a lighting device for a motor vehicle comprising one or more LEDs, at least one temperature sensor for detecting the temperature of at least one LED, a power supply of the LEDs serving switching power supply and the LED operation steuemdes control unit that communicates with the switching power supply and the temperature sensor.
  • LEDs In modern motor vehicles, lighting devices comprising one or more LEDs are increasingly being used, for example for better illumination of curves to be traveled in the form of a curve or cornering light.
  • the use as low beam is intended.
  • the problem with using individual LEDs or multiple discrete LED's exhibiting modules is that the LEDs must not exceed a certain limit temperature, otherwise they are irreversibly destroyed.
  • a temperature sensor To detect the LED temperature, a temperature sensor is provided in the prior art, which communicates with the control unit. If the temperature reaches a critical range, then in the prior art, the power supply is abruptly reduced, which in the following leads to a reduction in temperature, but equally also to a considerable reduction in brightness. However, such is not desirable.
  • the invention is therefore based on the problem to provide a lighting device that allows within certain limits, a temperature-sensitive LED control without serious loss of brightness.
  • a lighting device is provided with the features of claim 1.
  • a current interval is defined within which the output current of the switching power supply, which is given to the LEDs, can be varied depending on the temperature, the LED limit current is dimensioned so that given due to the current reduction decrease in brightness also in a tight limited interval between the maximum brightness at rated LED current and the brightness decreases when the LED limit current is applied.
  • the current regulation now takes place as a function of the detected temperature.
  • the lower limit of the current is just the LED limit current.
  • the predetermined value by which the brightness can be reduced without being recognized by the viewer's eye is according to the invention a maximum of 10%.
  • any other predetermined value, with respect to which the LED limit current is defined can be selected.
  • the LED limit current can be used approx. 60% of the rated LED current. This means that it is possible to lower the output current to 60% of the rated LED current, and then still move within the permitted brightness interval. A further current regulation would lead to an exceeding of the predetermined brightness value, which would then result in a noticeable reduction in brightness.
  • a maximum current reduction of 40% means that the heat development also decreases by a good third.
  • the actual value by which the brightness or the current can be reduced depends on the manufacturer or type of LED.
  • the control is carried out as described in dependence on the measured actual temperature. Basically, the LED is operated with the rated current. As the heat builds up, the temperature rises. From a certain temperature, the Stromabregelung begins, with the continuously measured LED temperature serves as a controlled variable.
  • the manipulated variable, ie the output current is changed so that a lower temperature level is adjusted, if this is possible by a current change in the specified current interval.
  • the control unit is expediently designed for automatically switching off the LEDs in order to prevent their destruction.
  • the current limit or Stromabregelung can be done in different ways.
  • a plurality of different resistances can be provided for this purpose in the switched-mode power supply, which are connected via the control unit as a function of the measured temperature for varying the output current depending on the required current limitation.
  • the resistors are designed so that a stepwise current reduction is possible, preferably to e.g. maximum 60% of the rated current.
  • the switching power supply can also be provided with a control element, in particular a transistor, which can be activated via the control device and which can be correspondingly activated in dependence on the measured temperature for varying the output current.
  • a control element in particular a transistor
  • This stepless control is possible via the transistor, the output current of the switching power supply, which corresponds to the LED current, are easily controlled to a desired value.
  • Fig. 1 shows in the form of a schematic representation of a lighting device 1 according to the invention, comprising a plurality of light sources in the form of three LED's 2a, 2b and 2c, each of which a control electronics 3a, 3b and 3c is assigned. These communicate with a control unit 4, which controls the control electronics via pulse width modulation signals.
  • a switching power supply 5 comprising a voltage converter 6, via which the vehicle electrical system voltage of 12 V DC voltage can be increased to the LED supply voltage of 20 V.
  • the output current of the switching power supply 5 and the voltage converter 6 can be set, that is, the output current given to the LEDs 2a-c can be varied here.
  • a temperature sensor 7 in the form of a PTC thermocouple is provided in the example shown, the output signal of which is given to the control unit 4. This now controls, for example, on the basis of a corresponding characteristic or the like as a function of the given temperature signal the switching power supply 5 to vary the output current depending on the given temperature.
  • ohmic resistances can be provided in the switched-mode power supply 5 or in the voltage converter 6, which are switched on depending on the signal from the control unit 4 and via which a stepwise adjustment of the output current is possible. It is also conceivable, however, for a control element in the form of a transistor to be provided in the switched-mode power supply 5 or in the voltage converter 6, which can be set in its on-state behavior via the output signal of the control device 4, which then causes the output current to change as a function of the temperature.
  • a maximum current reduction is starting from a maximum LED current, namely, the nominal current I nom of 100%, on a pre-defined limit LED current I limit permitted.
  • Fig. 2 Fig. 12 is a graph showing the ratio of the LED brightness in percent to the LED current in percentage.
  • the LEDs are lit at maximum brightness of 100%.
  • Such a decrease in brightness is hardly noticeable to the eye of the beholder. That is, with a considerable current reduction by 40% is an extremely low brightness reduction to a predetermined brightness value, here, for example, 5% (ie 95% brightness) accompanied.
  • a stronger current reduction then clearly leads to a significantly greater decrease in brightness than in the specified interval.
  • the current supplied to the LEDs via the control unit 4 can be measured in the interval between the rated current I rated limit current I limit can be varied to regulate to a temperature level at which the LEDs will not be damaged, without any noticeable loss of brightness would be associated with it. Nevertheless, a considerable reduction of the heat development can be achieved within this interval, so that for most applications, the current variation in the specified interval as a function of the temperature can be used to avoid exceeding the critical temperature range. Nevertheless, should the control limit I limit be lower than the actual temperature in order to be able to control a given temperature development, the switching off of the LEDs or of the entire module takes place via the control unit 4 expediently.
  • Fig. 1 shows as an example the construction of a lighting device, which serves to give a cornering or cornering light, to which the three LEDs, 2a - c are directed in different directions to the vehicle side.
  • a time-shifted switching operation of the LED's 2a - c is provided as a function of the actual steering angle, it is expedient, via the temperature sensor 7, only the temperature of that LED, which is turned on as the first and switched off when last as the last to detect, since the temperature the other LED's is at most equal to this LED, but usually below it.
  • the detection of the temperature of only one LED is representative of all others.

Landscapes

  • Lighting Device Outwards From Vehicle And Optical Signal (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Claims (6)

  1. Dispositif d'éclairage pour un véhicule automobile comprenant une ou plusieurs LED, au moins une sonde de température pour détecter la température d'au moins une LED, un bloc d'alimentation à découpage servant à l'alimentation électrique des LED et un contrôleur qui commande le fonctionnement des LED et qui communique avec le bloc d'alimentation à découpage et la sonde de température,
    caractérisé en ce
    que le courant de sortie du bloc d'alimentation à découpage (5) peut être varié par le biais du contrôleur (4) en fonction de la température détectée de l'au moins une LED (2a) à l'intérieur d'un intervalle entre le courant nominal de la LED (INenn) et un courant limite de LED (IGrenz) plus faible jusqu'auquel la luminosité diminue d'une valeur prédéfinie (ΔH) en comparaison de la luminosité lorsque le courant nominal de la LED (INenn) est appliqué, la valeur prédéfinie (ΔH) étant égale au maximum à 10 %.
  2. Dispositif d'éclairage selon la revendication 1, caractérisé en ce que le courant limite de LED (IGrenz) est égal à 60 % du courant nominal de la LED (INenn).
  3. Dispositif d'éclairage selon la revendication 1 ou 2, caractérisé en ce que plusieurs résistances différentes sont prévues dans le bloc d'alimentation à découpage (5), lesquelles peuvent être mises en circuit en fonction de la température mesurée pour faire varier le courant de sortie.
  4. Dispositif d'éclairage selon la revendication 1 ou 2, caractérisé en ce qu'un élément de régulation commandable par le biais du contrôleur (4), notamment un transistor, est prévu dans le bloc d'alimentation à découpage (5), lequel peut être commandé en fonction de la température mesurée pour faire varier le courant de sortie.
  5. Dispositif d'éclairage selon l'une des revendications précédentes, caractérisé en ce que le contrôleur (4) est configuré pour déconnecter automatiquement les LED (2a, 2b, 2c) à une température déterminée qui impose une diminution du courant de sortie au-dessous du courant limite de LED (IGrenz).
  6. Dispositif d'éclairage selon l'une des revendications précédentes, caractérisé en ce que les LED (2a, 2b, 2c) servent à générer un feu de changement de direction ou de virage.
EP05024986A 2004-11-19 2005-11-16 Dispositif d'eclairage pour voiture avec des LED's Expired - Lifetime EP1659831B1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102004055884A DE102004055884A1 (de) 2004-11-19 2004-11-19 Leuchteinrichtung für ein Kraftfahrzeug umfassend eine oder mehrere LED's

Publications (2)

Publication Number Publication Date
EP1659831A1 EP1659831A1 (fr) 2006-05-24
EP1659831B1 true EP1659831B1 (fr) 2012-02-15

Family

ID=35744799

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05024986A Expired - Lifetime EP1659831B1 (fr) 2004-11-19 2005-11-16 Dispositif d'eclairage pour voiture avec des LED's

Country Status (2)

Country Link
EP (1) EP1659831B1 (fr)
DE (1) DE102004055884A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007044339B4 (de) * 2007-09-17 2020-08-20 Tridonic Gmbh & Co Kg Leuchtdioden-Modul und Verfahren zur Steuerung eines Leuchtdioden-Moduls
CN101173757A (zh) * 2007-09-25 2008-05-07 东莞勤上光电股份有限公司 Led路灯过热保护方法
DE102008017483A1 (de) * 2008-04-03 2009-10-08 Steinel Gmbh Leuchtenvorrichtung
JP5971578B2 (ja) 2011-08-22 2016-08-17 パナソニックＩｐマネジメント株式会社 点灯装置、前照灯点灯装置及びそれを用いた前照灯並びに車両
US9060408B2 (en) * 2012-07-10 2015-06-16 Dialog Semiconductor Inc. Thermal de-rating power supply for LED loads
US9204524B2 (en) 2014-03-10 2015-12-01 Dynotron, Inc. Variable lumen output and color spectrum for LED lighting
US9907148B2 (en) 2014-03-10 2018-02-27 Dynotron, Inc. LED lighting system having at least one heat sink and a power adjustment module for modifying current flowing through the LEDs

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3705316A (en) * 1971-12-27 1972-12-05 Nasa Temperature compensated light source using a light emitting diode
DE19728763B4 (de) * 1997-07-07 2007-10-31 Reitter & Schefenacker Gmbh & Co. Kg Schaltungseinrichtung zum Schutz von strombetriebenen Leuchtmitteln, insbesondere von LEDs, zu Signal- oder Beleuchtungszwecken
DE19805771A1 (de) * 1998-02-13 1999-08-19 Hohe Gmbh & Co Kg Beleuchtungseinrichtung für Kraftfahrzeuge
DE19930174A1 (de) * 1999-06-30 2001-01-04 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Ansteuerschaltung für LED und zugehöriges Betriebsverfahren
JP2001078168A (ja) * 1999-09-08 2001-03-23 Sony Corp 表示装置、信号送受信装置、無線伝送装置及び信号送受信方法
US7262752B2 (en) * 2001-01-16 2007-08-28 Visteon Global Technologies, Inc. Series led backlight control circuit
EP1313353A1 (fr) * 2001-11-19 2003-05-21 Nokia Corporation Procédé et dispositif pour commander une diode LED
JP4511784B2 (ja) * 2001-12-20 2010-07-28 オスラム オプト セミコンダクターズ ゲゼルシャフト ミット ベシュレンクテル ハフツング Ｌｅｄアレイ及びｌｅｄモジュール
GB0204212D0 (en) * 2002-02-22 2002-04-10 Oxley Dev Co Ltd Led drive circuit
DE10214447A1 (de) * 2002-03-30 2003-10-16 Hella Kg Hueck & Co Regeleinrichtung zum Regeln von elektrischen Leuchtmitteln und Scheinwerfer mit einer solchen Regeleinrichtung
US7635957B2 (en) * 2003-09-04 2009-12-22 Koninklijke Philips Electronics, N.V. LED temperature-dependent power supply system and method

Also Published As

Publication number Publication date
EP1659831A1 (fr) 2006-05-24
DE102004055884A1 (de) 2006-05-24

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